Fertilizers are commonly used to provide nutrients essential to the growth of plants. They m be in a granule or powder form and may be applied to the soil or to plant tissues. Fertilizers may contain in varying proportions the following nutrients: Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg), Sulfur (S), Copper (Cu), Manganese (Mn), Iron (Fe), Zinc (Zn) and Boron (B). The list of commonly used fertilizers includes, but is not limited to, calcium sulfate, urea, calcium nitrate, calcium ammonium nitrate, potassium chloride, potassium nitrate, magnesium ammonium phosphate (referred to as struvite), iron phosphate, ammonium phosphate and ammonium sulfate nitrate.
The application of fertilizers, while beneficial to plants, also pose significant risks. Applied in excess, fertilizers may be poisonous to plants and also contaminate the subsurface water. The effectiveness of fertilizers is degraded through oxidation, evaporation and leaching into ground water. Microbes also degrade fertilizers by immobilization or oxidation.
One solution to the fertilizer loss of effectiveness is to change the chemical formulation and apply coatings onto the fertilizer particles to control the rate of release of the nutrients into the soil. Ideally, the nitrogen release time in slow release fertilizers is about one month. Slow release fertilizers vary in effectiveness, but few achieve this release rate.